A method and apparatus for determining a volume flow are known from applicants' copending German patent application P 42 43 077.1 (laid-open Jun. 24, 1993). In the latter the flow rate and filling level are determined at successive locations in the axial extension of the measuring line and therefore in the flow direction,, because the measuring devices for determining the fluid flow rate and the fill level are arranged in succession In the flow direction. In the case of rapidly changing rate profiles and fill level distributions imprecisions can consequently occur in a measurement.
DE 41 08 138 A1 discloses a volume flow determination apparatus which, for improving the measured result, on dropping below a certain fill level in the measuring line has an electromagnet arrangement specifically optimized for partial fill levels and which is activated in place of an electromagnet arrangement responsible for the operation of the completely filled measuring line.
DE 37 37 607 A1 discloses a volume flow determination method, in which a measured value is determined at different levels and then compared with a reference value and in which the mass of the fluid flowing through is determined batchwise.